The great promise of digital PCR is the potential for unparalleled precision enabling accurate measurements for genetic quantification. Target nucleic acid molecules of a sample requiring quantification are distributed evenly on a digital PCR consumable with many partitions and subjected to a PCR reaction. Partitions with template show amplification of the target nucleic acid and partitions lacking template do not show amplification. The observations are typically fitted with the Poisson model to predict the number of molecules present in the sample under measurement.
A basic assumption of the Poisson model is that molecules are equally likely to be present in any given partition, implying that the partitions are of equal size. For microfluidics, functioning at sub nanoliter volumes, this assumption may easily be violated. Recently, discussions of the detrimental effects of partition size variation on digital PCR quantification results, particularly at high concentrations, have come to light.